-NRLF 


1    DD7 


A Uiz  17 


Experiments  in  Educability 


#)>  STEVENSON  SMITH 

,4s  Abstract  of  the  thesis  presented  to  the  faculty  of  tht 

Graduate  School  of  the  University  of  Pennsylvania 

in  partial  fulfilment  of  the  requirements 

for  the  degree  of  Doctor  of  Philosophy 


03s 


REGULATION  IN  BEHAVIOR 

Several  years  ago  there  appeared  in  Nature  an  account 
of  a  statistical  inquiry  into  sex  determination.  The  results 
indicated  that  children  born  to  young  mothers  were  predom- 
inantly girls  and  that  those  born  to  old  mothers  were  pre- 
dominantly boys.  Whether  this  hypothesis  has  been  borne 
out  by  further  results  I  do  not  know,  but  assuming  it  to  be  a 
law,  it  is  an  example  of  what  has  been  called  regulation  in 
behavior.  The  purpose  which  such  a  process  serves  is  clear. 
When  there  is  a  shortage  of  women  in  a  community  girls  are 
likely  to  marry  when  very  young,  due  to  the  increased  op- 
portunity afforded  them  on  account  of  the  under-supply  of 
more  mature  women.  If  such  marriages  result  in  a  number 
of  female  infants  greater  than  the  normal  expectation,  the 
balance  between  supply  and  demand  is  thereby  reestablished. 
A  similar  compensation  is  had  when,  in  a  society  where  fe- 
males predominate,  and  hence  are  not  married  so  early  in 
life,  male  offspring  are  in  excess. 

The  world  is  full  of  instances  of  this  sort.  Organisms 
utilize  the  very  difficulties  they  encounter  in  order  to  bring 
about  the  removal  of  these  difficulties.  Their  make-up  in- 
sures this  regulation.  They  do  not  depend  on  outside  guid- 
ance to  carry  them  through  adverse  situations.  The  adverse 
situations  in  combination  with  an  organism  are  self-eliminat- 
ing. Of  course  this  is  not  always  true  for  the  individual, 
but  the  social  group,  which  is  the  larger  organism,  survives 
because  the  procreation  of  its  parts  is  as  rapid  as  their 
destruction. 

We  otten  so  construct  a  piece  of  machinery  that  this 
principle  of  auto-adjustment  holds  in  its  behavior.  This  is 
done  so  that  we  may  not  have  to  manipulate  it  and  direct  it 
to  any  great  extent.  The  floating  ball  disconnects  the  circuit 
and  stops  the  pump  when  the  tank  is  full.  The  pendulum 
swings  to  one  side  and  releases  the  air  pressure  which  tilts 
the  wing  tip  of  the  aeroplane  when  a  gust  of  wind  causes  it 
to  pitch  or  roll,  and  this  restores  equilibrium.  The  electric 


ONE] 


310420 


V* 


sterilizer  is  supplied  with  a  soft  metal  plug  which  melts  off 
and  releases  a  spring,  so  breaking  the  circuit,  when  the  water 
is  exhausted.  Otherwise  the  rheostat  would  be  burned  out. 
But  now  the  heat  prevents  itself  from  being  dangerous.  A 
general  statement  of  these  and  other  forms  of  regulation 
might  be  valuable.  It  might  indeed  serve  as  a  rule  of  thumb 
for  inventors. 

Bancroft1  gives  many  excellent  examples  of  regulatory 
behavior  as  illustrating  his  "universal  law."  This  law  is 
that  "a  system  tends  to  change  so  as  to  minimize  an  external 
disturbance."  Some  of  the  cases  he  notes  are: 

The  readjustment  of  prices  through  supply  and  demand. 

Tears  caused  by  and  discharging  an  irritating  substance 
from  the  eye. 

A  splinter  causing  its  own  sloughing  out. 

In  chemistry,  the  occasional  prevention  of  further  re- 
action by  some  reaction  products. 

An  insult  causing  a  response  which  may  prevent  further 
insult. 

The  bending  of  trees  to  spill  the  wind. 

It  is  certainly  tautologous  to  say  that  organisms  behave 
along  lines  of  least  resistance,  for  our  only  definition  of  least 
resistance  is  the  resistance  that  a  system  is  first  to  overcome. 
But  any  suspicion  that  the  statement  of  Bancroft's  law  falls 
short  in  a  like  way  of  being  a  synthetic  judgment,  is  removed 
after  he  has  clarified  it  by  illustration  and  comment. 

Adaptation  of  a  group  of  animals  or  plants  by  selection 
is  a  case  of  regulation  if  we  regard  the  group  as  an  organism. 
The  capacity  for  all  the  responses  is  not  resident  in  all  the 
individual  animals  or  plants,  but  is  distributed  among  the 
parts  (individuals)  of  the  entire  organism  (group).  The 
existence  of  the  organism  is  maintained  along  with  the  life 
of  those  parts  which  respond  adaptively  to  the  present  con- 
dition, notwithstanding  the  death  of  those  parts  which  are 
not  adjusted  so  to  respond.  This  is  shown  in  the  adaptation 
of  wheat  to  climate.  A  bushel  of  late  ripening  wheat  will 

i  Bancroft,   W.   D.,   "A   Universal    Law,"   Jour,   Am.    Chem.    Soc., 
XXXIII.,    No.    2,    February,    1911. 

[TWO 


contain  some  grains  of  early  ripening  wheat.  Planted  under 
certain  conditions,,  these  latter  alone  will  mature,  but  they 
will  serve  as  seed  for  the  next  crop,  which  will  inherit  their 
characteristics  for  the  most  part,  and  which  will  be  almost 
entirely  early  ripening  wheat. 

When  an  apparently  new  structural  adaptation  is  de- 
veloped in  an  organism  by  a  set  of  new  conditions,  the  pre- 
sumption is  that  the  organism's  capacity  for  this  change  of 
structure  was  previously  resident  in  the  organism,  and  not 
that  the  change  was  wholly  caused  by  the  new  condition. 
The  condition  was  the  necessary  factor  which  had  to  be  added 
to  the  organism's  potential  capacity,  in  order  that  the  adapta- 
tion should  result.  An  organism  may  in  this  way  be  so 
adjusted  as  to  respond  adaptively  to  any  one  of  a  number  of 
possible  conditions  which  may  be  mutually  exclusive.  So  when 
one  response  is  realized,  the  others  may  be  latent.  This 
is  shown  by  the  substitution  of  hair  for  wool  in  the  coat  of 
a  sheep  that  is  taken  to  a  warmer  climate.  In  the  domain 
of  behavior  a  similar  rule  is  obvious.  Here  a  given  stimulus 
calls  forth  a  particular  reaction  which  is  especially  fitted  to 
the  situation. 

The   Vital   Manifold 

Organisms  living  in  an  environment  of  changing  con- 
ditions are,  for  the  most  part,  constantly  readjusting  them- 
selves to  the  change.  They  avoid  bad  conditions  and  seek 
better.  Or,  when  an  unfavorable  condition  can  not  be  avoided, 
a  change  takes  place  in  their  structure  which  makes  it  pos- 
sible for  them  to  live  in  that  condition.  If,  when  in  a  certain 
medium  some  metabolic  change  takes  place  in  them,  which 
to  be  set  right  demands  some  other  medium,  they  seek  out 
that  other  medium  either  by  trial  and  error  reactions  or,  fol- 
lowing certain  clues  present  in  their  surroundings,  by  some 
specially  appropriate  instinctive  or  habitual  reaction.  If  we 
admit  that  such  processes  are  regulatory,  we  have  made  a 
beginning  towards  defining  regulation.  We  may  further  say 
that  it  is  characteristic  of  organisms  having  a  certain  struc- 

THREE] 


ture.  It  is  the  result  of  the  interaction  of  such  organisms 
and  their  media.  The  organism  and  the  media  constitute  a 
manifold  which,  though  constantly  operating,  so  functions  as 
to  prevent  disintegration  of  the  organism.  The  life-long  sta- 
bility of  arrangement  possessed  by  the  organism  and  its 
offspring  further  differentiates  it  from  the  media  and  makes 
most  significant  the  distinction  between  biology  and  the 
inorganic  sciences.  The  field  of  the  science  of  animal  be- 
havior of  which  the  processes  in  such  a  manifold  constitute 
the  data,  is  in  part  hardly  to  be  distinguished  from  some  of 
the  subject-matter  of  dynamic  biology.  The  former  science, 
however,  always  classifies  these  processes  on  the  basis  of  the 
regulation  which  they  display. 

Negative   Regulation 

Regulation  occurs  when  any  process  in  the  manifold 
which  reduces  the  stability  of  the  organism  results  in  such 
a  change,  either  in  the  media  (through  the  organism's  mi- 
gration or  otherwise)  or  in  the  organism  itself,  that  the 
stability  of  the  organism  is  regained,  so  that  the  deviation 
toward  instability  has  come  to  be  the  cause  of  its  own  remedy. 
Such  regulation  is  the  avoidance  of  those  states  in  the  or- 
ganism or  of  those  conditions  in  the  media  which  are  or  have 
become  unfavorable  to  the  stability  of  the  organism,  so  let 
us  call  it  negative  regulation. 

Frequent  examples  of  negative  regulation  are  found  in 
the  behavior  of  inorganic  manifolds,  of  plants,  and  of  the 
lower  animals.  When  a  boat  in  a  heavy  sea  rolls  to  one  side 
it  rights  itself  into  the  perpendicular  again.  It  does  this 
because  of  the  fact  that  the  further  it  tilts  from  the  per- 
pendicular the  greater  is  the  leverage  by  which  the  pull  of 
gravity,  which  tends  to  bring  it  back,  is  applied.  Its  behavior 
conforms  to  our  definition  of  negative  regulation.  The  way 
in  which  paramoecium  retains  favorable  conditions  must  be 
described  by  the  same  principle.2  The  valve  action  at  the 
boundary  of  the  optimum  will  work  for  the  animal's  good  in 

2Jennings,    "Behavior   of   Lower  Organisms." 

[FOUR 


either  novel  or  familiar  conditions.  A  river  (organism) 
shows  regulation  in  migrating  from  its  original  channel  to 
one  of  greater  stability,  and  in  overcoming  obstacles,  such  as 
log  jams  or  landslides,  which  serve  as  the  cause  of  their  own 
remedy. 

In  the  above  examples  correction  is  the  result  of  the 
excess  of  process,  or  deviation  from  stability.  The  correction 
and  the  condition  which  needs  correction  may,  however,  both 
be  the  results  of  the  same  cause,  having  no  causal  effect  on 
each  other.  For  instance,  in  crayfish  oxygen  starvation  is 
corrected  by  the  very  activity  which  causes  it,  namely,  walk- 
ing. The  gills  are  placed  so  as  to  be  moved  by  the  legs, 
for  which  reason  walking  causes  both  depletion  and  repair 
of  the  oxygen  content  of  the  blood.  Another  example  is 
found  in  the  protective  color  changes  in  the  coat  of  northern 
mammals.  These  changes  are  possibly  not  the  result  of  the 
color  environment  (the  seasonal  variation  of  which  is  a  devia- 
tion toward  instability),  but  rather  the  result  of  some  ac- 
companying condition  such  as  food  or  temperature  plus  certain 
internal  factors.  That  is,  the  brown  fur  does  not  become 
white  because  of  the  whiteness  of  the  snow.  The  cause  to 
which  is  due  in  part  the  occurrence  of  the  snow,  namely,  a 
decrease  in  temperature,  is  largely  responsible  for  the  adapt- 
ive change  in  the  color  of  the  fur.  Again,  for  example,  the 
sunshine  which  on  a  summer  day  would  otherwise  overheat 
a  man,  is  in  part  the  cause  of  the  breezes  which  assist  in 
keeping  him  cool.  The  cause,  that  is,  which  produces  the 
deviation  from  the  optimum  brings  about  also  a  condition 
which  helps  to  restore  the  optimum. 

We  may  then  occasionally  find  this  relation  between 
the  deviation  from  stability  and  its  means  of  correction.  The 
mutual  cause  of  these  two  processes  may  indeed  be  in- 
definitely remote.  This  phase  of  regulation  is  not  recog- 
nized in  the  above  definition,  so  we  may  add:  Negative  regu- 
lation also  occurs  when  a  process  in  the  manifold  which  is 
the  cause  of  a  deviation  from  stability  results  independently 
in  its  correction. 

FIVE] 


Positive  Regulation 

An  organism  may  be  so  constituted  that  it  reacts  to  some 
condition  which  is  favorable,  adapting  itself  so  as  to  obtain 
benefit  from  it,  even  when  failure  so  to  react  to  the  condition 
would  cause  it  no  more  harm  than  the  loss  of  an  unusual 
benefit.  This  form  of  reaction  is  sometimes  given  to  a  con- 
dition which  the  organism  does  not  reach  by  locomotion, 
such  as  a  condition  which  is  generally  periodic  and  has  no 
fixed  spacial  position (  e.  g.,  a  weather  condition).  But  if 
the  organism  has  means  of  locomotion,  the  reaction  more 
usually  involves  a  movement  toward  the  favorable  condition. 
This  favorable  condition  may  be  only  occasionally  present 
or  it  may  be  only  occasionally  needed  by  the  organism.  The 
favorable  condition  to  which  the  organism  reacts  may  be  at 
a  distance  from,  or  may  impinge  upon,  the  organism.  If  it 
is  at  a  distance  it  must  act  mediately  upon  the  organism  and 
the  organism  must  have  the  power  of  locomotion  in  order  to 
take  advantage  of  it.  The  favorable  condition  may  be  rela- 
tively fixed  in  space,  such  as  air  at  the  top  of  the  water,  or 
it  may  be  relatively  fixed  in  time,  such  as  the  regular  re- 
currence of  sunlight.  To  distinguish  this  form  of  regulation 
let  us  call  it  positive. 

Positive  regulation  occurs  when  some  change  in  the  en- 
vironment or  in  the  physiological  state  of  the  organism  causes 
such  an  adaptive  reaction  of  the  organism  or  such  an  alteration 
in  the  media  that  the  interaction  of  the  newly  arranged 
organism  and  media  which  follows  brings  about  increased 
stability  in  the  organism.  In  such  a  process  both  organisms 
and  media  have  a  double  function.  The  media  act  first  as 
the  stimulus  to  the  organism's  adaptive  reaction  and  second 
as  a  contributing  cause  of  the  increased  stability  of  the 
organism.  The  organism  likewise  must  be  set  or  arranged 
to  adjust  or  orient  itself  to  the  changed  conditions  and  also 
to  interact  with  the  novel  media  so  as  to  cause  increased 
stability  in  the  new  relation.  The  squirrel's  storing  its  food, 

[SIX 


the  butterfly's  seeking  its  mate,  and  the  prospector's  digging 
for  gold  are  all  examples  of  positive  regulation. 

In  positive  regulation  the  favorable  condition  and  the 
adaptive  change  do  not  always  have  the  direct  relation  of 
cause  and  effect.  They  may  be  as  well  results  of  a  single 
cause.  This  is  especially  true  in  the  higher  forms  of  be- 
havior, such  as  the  behavior  of  a  group  of  sympathetic 
organisms  in  a  colony  or  society.  For  instance,  Greek  phil- 
osophy was  a  cause  which  has  ramified  into  many  results. 
Largely  because  of  it,  and  of  the  development  which  it 
caused,  the  present-day  students  write  their  books  on  science 
or  philosophy,  because  of  it  there  are  laboratories,  without 
which  these  books  would  have  lacked  much  material,  and 
printing  presses,  without  which  the  volumes  would  never  have 
reached  their  readers.  That  same  early  philosophy  is  the 
inheritance  of  the  people  and  without  it  the  modern  book 
would  not  be  understood.  As  another  example,  when  the 
hot  weather  in  spring  impels  birds  to  migrate  northward  it 
causes  also  those  changes  in  the  country  further  north  which 
produce  food  and  the  proper  conditions  for  raising  the  young. 
So  we  may  add:  Positive  regulation  occurs  when  a  process 
in  the  manifold  which  is  the  cause  of  some  potentially  favor- 
able condition  results  independently  in  an  adaptive  change 
by  which  the  organism  takes  advantage  of  it. 

Both  positive  and  negative  regulation  may  take  place  as 
the  result  of  a  change  merely  in  the  physiological  state  of 
the  organism  and  not  be  due  to  any  variation  in  the  media. 
Negative  regulation  is  seen  under  such  conditions  in  the 
reactions  of  the  over-fed  sea  anemone  away  from  food,  or  in 
behavior  of  a  dog  that  after  a  time  moves  further  away 
from  a  fire  the  heat  of  which  had  at  first  attracted  him. 
Positive  regulation  takes  place  under  like  conditions  when 
respiration  is  increased  due  to  exercise,  or  when  the  hungry 
animal  goes  out  to  search  for  food  to  which  previously  it 
had  been  indifferent.  Judgment  and  reason  in  the  higher 
animals  furnish  the  best  examples  under  these  conditions  for 
positive  regulation.  Positive  regulation  usually  results  in  an 

SEVEN] 


increased  margin  of  stability  which  is  insurance  against 
future  dangers  and  permits  the  organism  some  rest  from 
the  activities  of  negative  regulation.  The  two  forms  of 
regulation  are  combined  in  the  food  reaction  of  most  an- 
imals. Hunger  results  in  migratory  search  after  food  as 
well  as  in  its  capture.  Many  animals,  however,  capture 
food  for  future  use  when  the  conditions  of  negative  regu- 
lation are  not  present.  The  two  forms  of  regulation  are, 
for  instance,  combined  when  a  man  rises  in  the  morning  partly 
because  he  is  no  longer  comfortable  in  bed  and  partly  be- 
cause he  hears  the  water  running  into  his  tub. 

The  direct  interaction  between  the  conditions  existing 
at  any  given  time  as  well  as  the  resulting  adaptations  in  the 
manifold  may  be  described  as  follows: 

In  negative  regulation  unfavorable  media  (present  or 
at  a  distance)  may  cause  a  change  in  the  organism  that 
makes  it  either  resist  such  media,  or  avoid  or  migrate  from 
such  media,  or  analyze  or  synthesize  such  media  into  in- 
nocuous or  favorable  media.  Or  some  unfavorable  part  or 
process  in  the  organism  may  cause  its  own  elimination  or 
discontinuance,  either  by  interaction  with  the  media,  or  by 
action  within  the  organism,  or  by  both  of  these. 

In  positive  regulation  favorable  media  (present  or  at 
a  distance)  may  cause  a  change  in  the  organism  that  makes 
it  either  interact  with  such  media  or  enter  into  or  migrate  to 
such  media.  Or  innocuous  media  (present  or  at  a  distance) 
may  cause  a  change  in  the  organism  that  makes  it  analyze  or 
synthesize  such  media  into  favorable  media.  Or  some  favor- 
able part  or  process  in  the  organism  may  cause  its  own  main- 
tenance or  continuance,  either  by  interaction  with  the  media 
or  by  action  within  the  organism  or  by  both  of  these. 


[EIGHT 


EXPERIMENTS  IN  EDUCABILITY  OF 
PARAMOECIUM 

Reactions  to  Touch.  The  purpose  of  the  following  ex- 
periments was  to  determine  what  kind  of  modi  f  lability  is 
shown  by  Paramoecium  due  to  recurring  experiences  of  the 
same  kind.  For  this  purpose  first  a  capillary  tube  was  se- 
lected of  a  bore  smaller  than  the  length  of  the  Paramoecium 
and  larger  than  his  width.  The  animal  was  caught  by  the 
upward  suction  of  the  tube  and  the  tube  was  then  placed  on 
a  movable  carriage,  so  the  animal  could  always  be  kept  in 
the  field  of  the  microscope  no  matter  what  part  of  the  tube 
it  might  be  swimming  through. 

Once  in  the  tube  the  Paramoecium  swims  to  the  forward 
end  and  upon  reaching  the  meniscus  jerks  backward  for 
several  times  its  own  length,  then  approaches  again  in  a  wider 
spiral  than  before.  This  backing  and  approaching  takes 
place  at  least  a  dozen  times  and  later  the  Paramoecium  set- 
tles down  to  a  pecking  movement,  revolving  anti-scriwwise 
about  the  meniscus  and  attacking  about  five  places  in  its 
circumference. 

In  the  original  approaching  and  retreating  both  move- 
ments may  be  either  screwwise  or  anti-screwwise.  In  ap- 
proaching, both  the  screwwise  and  anti-screwwise  movements 
give  about  the  same  width  of  spiral,  namely,  a  very  slight 
one.  If  the  retreat  is  made  anti-screwwise  a  relatively 
straight  course  is  followed,  the  spiral  being  hardly  notice- 
able. If  the  retreat  is  screwwise  a  very  wide  spiral  re- 
sults. 

In  most  cases  the  animal  after  a  varying  time  bends  its 
anterior  end  around  toward  the  aboral  side,  forming  a  "U" 
with  its  body,  and  after  a  number  of  jerks  succeeds  in  re- 
versing the  position  of  its  body  in  the  tube.  In  all  cases  it 
turns  toward  the  aboral  side,  thus  using  the  long  creeping 
cilia  near  the  buccal  groove  to  obtain  a  hold  on  the  side  of 
the  tube. 

NINE] 


As  this  facing  about  in  the  tube  is  repeated,  the  time 
taken  for  each  turn  may  be  longer  than  for  the  last,  the 
animal  finally  dying  of  apparent  fatigue,  or,  if  the  tube  is  not 
so  small  that  too  violent  an  effort  is  required  of  the  animal, 
the  time  may  gradually  be  shortened  and  a  most  surprising 
aptitude  of  turning  be  developed.  Paramoecia  from  a  vig- 
orous culture  give  better  results  than  poorly  nourished  ones. 
Under  optimum  conditions  there  was  \found  a  reduction  of 
turning  time,  after  the  animals  had  been  in  the  tube  for 
twelve  hours  or  more,  from  four  or  five  minutes  to  a  second 
or  two,  which  is  the  minimum  time* ,  in  which  the  turn  can 
be  made. 

Often  the  Paramoecium  will  rest  for  a  long  period  at 
once  meniscus,  slowly  circling  around  with  its  buccal  groove 
resting  against  the  air  surface.  When,  however,  the  effort 
is  made  to  reverse,  the  shortening  of  time  in  the  practiced 
individuals  is  very  apparent. 

Reactions  to  temperature.  In  these  experiments  a 
capillary  tube  was  selected  large  enough  to  allow  the  Para- 
moecia to  reverse  their  direction  without  touching  its 
sides,  and  in  which  two  Paramoecia  could  pass  each  other 
without  difficulty.  A  number  of  individuals  were  taken  up 
in  this  tube  and  the  tube  was  placed  on  a  carriage  having 
two  large  glass  supporting  tubes  through  which  water  of 
different  temperatures  was  passing  and  on  which  the 
capillary  tube  rested. 

While  hot  water  was  flowing  through  one  support  and 
cold  water  through  the  other  the  temperatures  could  be  re- 
versed, so  that  the  cold  water  would  flow  through  the  one 
and  the  hot  water  through  the  other.  Thus  the  distribution 
of  temperature  in  the  capillary  tube  could  be  reversed.  By 
cold  water  is  meant  water  at  normal  temperature  to  which  the 
animal  gives  no  reaction. 

As  soon  as  the  capillary  tube  is  heated  at  one  end  by 
contact  with  the  hot  support,  the  Paramoecia  at  that  end 
dart  about  at  random  until  they  are  headed  toward  the  cool 
end  of  the  tube  and  even  then  do  not  swim  to  the  cool  end 

[TEN 


at  first  but  often  turn  back  to  the  hot  end  several  times  be- 
fore finally  swimming  over  to  the  cool  water.  Once  ar- 
rived at  the  cool  end  the  Paramoecia  do  not  stay  there,  but 
turn  and  start  back  to  the  hot  water.  In  this  way  a 
Paramoecium  may  traverse  the  length  of  the  tube  a  dozen 
times  or  more  before  coming  to  rest  at  the  cool  end  of  the 
tube.  As  the  animals  leave  their  resting  place  at  the  warm 
meniscus  in  obedience  to  the  repeated  reversing  of  tem- 
peratures in  the  tube,  their  movements  become  slower  and 
more  regulated  and  they  seldom  turn  more  than  once  toward 
the  cold  water  before  swimming  in  that  direction.  It  is  not 
significant  to  express  this  modification  of  behavior  in  terms 
of  time  for,  although  the  time  involved  in  getting  away  from 
the  heated  end  of  the  tube  is  somewhat  reduced  as  the 
stimulus  recurs,  it  is  the  suitability  of  the  movement  to  ac- 
complish the  result  which  characterizes  the  later  reactions. 
In  these  the  actual  locomotion,  is  slower  but  the  random 
movements  give  place  to  more  determined  ones. 

The  influence  of  an  associated  past  experience  upon  the 
reaction  to  a  given  stimulus.  Although  in  the  following  ex- 
periments the  observations  gave  nothing  but  negative  results, 
these  results  serve  to  fix  the  limits  of  educability  in  Para- 
moceium.  Although  Paramoecium  profits  by  experience,  as 
seen  in  the  above  sections,  it  does  not  show  associative  memory 
such  as  Loeb  would  demand  as  the  criterion  of  consciousness. 

The  conditions  of  the  first  experiment  were  these.  Para- 
moecia were  placed  in  a  trough  having  an  extremely  thin 
glass  bottom  and  this  trough  was  immersed  in  a  partitioned 
box  containing  hot  and  normally  cool  water  on  the  two  sides, 
so  that  the  bottom  of  the  trough  was  kept  cool  on  one  half 
and  warm  on  the  other.  There  was  a  distinct  line,  not  cor- 
responding exactly  to  the  partition  of  the  under  box,  at 
which  the  Paramoecia  approaching  from  the  cool  side  would 
turn  back.  A  light  was  fixed  above  the  trough  and  a  screen 
interposed  so  that  a  shadow  fell  covering  the  warm  area  and 
a  minute  part  of  the  cool  area  beyond  the  reaction  line. 
The  white  Paramoecium  which  was  here  used,  gives  no  re- 

ELEVEN] 


action  to  light  or  darkness  and  it  was  hoped  that  by  allow- 
ing the  animals  to  experience  darkness  whenever  they  ex- 
perienced heat  they  might,  when  the  heat  was  removed,  re- 
act negatively  to  darkness.  This  they  did  not  do,  however, 
though  one  group  of  Paramoecia  were  allowed  to  experience 
the  two  conditions  together  for  fifteen  hours,  one  for 
twenty-four  hours,  and  one  for  forty  hours. 

Another  experiment  of  a  somewhat  similar  kind  was 
performed  in  which  it  was  tried  to  bring  about  the  associa- 
tion of  heat  and  gravity.  A  small  tube  was  bent  into  an 
L  shape  and,  after  some  Paramoecia  had  been  drawn  up  into 
it,  was  placed  so  that  one  leg  was  horizontal  and  the  other, 
rising  from  this,  was  vertical.  At  the  top  of  the  vertical  leg 
was  placed  a  hot  metal  rod  in  contact  with  the  glass  and 
kept  at  a  constant  temperature.  If  Paramoecia  show 
geotropism,  (More:  Am.  Jour.  Phys.,  vol.  9,  pp.  238  ff.) 
this  irritability  to  gravity  should  be  more  easily  associated 
with  heat  than  could  light,  which,  although  it  must  make 
some  impression  on  the  organism,  does  not  cause  normally 

an   avoiding    reaction. 

Whenever,  the  Paramoecia  swam  up  the  vertical  leg  of 
the  tube  they  received  a  heat  stimulus  which  caused  them 
at  first  to  jerk  backwards  and  after  many  random  trials  to 
swim  downward  to  the  cool  water.  Although  these  conditions 
were  kept  unchanged  for  as  long  as  three  days  the  Paramoecia 
never  learned  to  avoid  the  vertical  leg  of  the  tube.  In  the 
end  they  did  not  react  as  violently  to  the  heat  and  did  not, 
as  at  first,  swim  occasionally  past  the  hot  metal  rod.  Also 
they  seemed  later  to  develop  greater  sensitivity,  reacting  to 
the  heat  before  getting  as  close  to  the  metal  rod. 

CONCLUSION 

Paramoecium  is  educable  in  that  its  behavior  may  be 
modified  to  show  the  results  of  practice,  both  in  a  reduction 
of  the  time  involved  in  performing  a  movement  and  in  the 
increase  in  suitability  of  the  movement  to  accomplish  the 
appropriate  result. 

[TWELVE 


In  so  far  as  the  tests  here  apply,  there  is  no  evidence 
of  associative  memory  in  Paramoecium. 

The  reversing  movement  above  described  is  in  the 
nature  of  a  positive  reaction. 


THIRTEEN] 


SOME  RESULTS  OF  TRAINING  A  GUINEA  PIG 

Description  of  the  Maze. 

The  maze  used  in  these  experiments  consisted  of  a 
straight  passage  which  ran  for  eighteen  inches  from  the 
entrance  to  a  point  where  two  other  passages  turned  at 
right  angles  from  it,  running  to  the  right  and  to  the  left. 
Three  inches  beyond  this  point  the  right  passage  turned 
again  to  the  right  and  the  left  passage  to  the  left,  both  open- 
ing through  doorways  into  an  area  outside  the  maze. 

Doors  were  made  of  sheet  zinc  and  were  swung  from  the 
top.  The  exit  doors  could  open  only  outward  and  the  entrance 
door  could  open  only  inward.  Thus  the  animal  having  entered 
the  maze  could  pass  out  through  the  exit  doors.  These 
doors  were  provided  with  hooks  by  which  either  could  be 
locked  at  will.  The  outside  measurement  of  the  box  was 
seventeen  by  twenty-six  inches. 

In  order  to  pass  through  the  maze  the  animal  enter- 
ing had  to  choose  either  the  right  or  the  left  passage.  This 
choice  was  involved  in  most  of  the  following  experiments 
with  the  maze.  An  albino  male  Guinea  pig  was  used  as  the 
subject  in  these  tests.  He  was  about  four  months  old  when 
first  used  and  about  seven  and  a  half  months  old  when  the 
tests  ended. 

Habit  Formation  in  the  Maze. 

The  Guinea  pig  had  been  accustomed  to  come  to  the  edge 
of  his  cage,  when  the  side  of  it  was  rapped  on,  in  order  to 
get  a  bite  of  carrot  which  was  held  in  the  experimenter's 
hand.  In  this  first  experiment  the  carrot  was  held  in  the 
first  passageway  of  the  maze  and  knocked  frequently  against 
the  wooden  side.  The  Guinea  pig  being  outside  the  entrance 
door,  reacted,  as  he  had  learned  to  do  in  his  next  box,  by 
hunting  about  for  the  carrot  in  the  neighborhood  of  the 
source  of  sound. 

After  the  pig  had  learned  to  enter  the  entrance  door 
he  was  allowed  to  do  so  and  here  to  eat  a  little  of  the  carrot, 

[FOURTEEN 


which  was  then  removed  and  rapped  against  the  wood  beyond 
the  right  doorway.  The  left  doorway  was  locked.  After 
the  first  trial,  rapping  to  indicate  the  position  of  the  food 
was  left  off.  The  carrot  was  shifted  back  and  forth  and 
the  time  taken  by  the  pig  to  follow  through  the  respective 
doors  was  recorded.  This  measurement  began  when  the 
pig  had  just  finished  chewing  one  mouthful  and  was  reach- 
ing for  another,  the  carrot  being  removed  at  that  time.  The 
measurement  ended  when  the  animal  had  passed  through  the 
door  and  it  had  fallen  shut  behind  him.  Thus  there  were 
two  series  of  measurements;  one  of  the  time  taken  to  enter 
the  maze  and  one  of  the  time  taken  to  leave  it.  These  are 
expressed  in  the  following  table.  The  trials  in  each  series 
were  taken  consecutively,  a  period  of  several  hours  elapsing 
between  the  series. 

Into     Maze  No.TrialsAv.  of  All  A.  D.  Av.  Firsts.  A.D.  1st  Trial 

Series   1  11          168.9          222.6          553.  324.7          1040. 

Series   2 

Series   3 

Series   4 

Out  of  Maze 

Series  1 

Series   2 

Series  3 

Series   4 

Series   5 

Series  G 

The  measurements  in  all  the  tables  are  given  in  seconds. 

Antagonistic  Habit  Formation  and  Cross   Training. 

After  an  interval  of  one  hundred  and  three  hours,  the 
Guinea  pig  was  returned  to  the  maze.  This  time  the  right 
door  was  locked  and  the  left  door  was  unlocked.  There 
was  no  difference  in  appearance,  that  would  be  noticeable 
to  the  pig,  between  the  maze  now  and  before,  because  the 
means  of  locking  the  door  was  a  wire  nail,  driven  into  the 
wood  at  the  side  of  the  door  and  bent  to  an  angle  of  ninety 
degrees,  which  could  be  turned  so  as  to  prevent  the  door 
from  swinging  and  was  visible  only  from  the  outside.  A 
turn  in  the  direction  opposite  to  that  which  the  Guinea  pig 
had  learned  had  now  to  be  made  before  he  could  leave  the 
maze.  The  carrot  was  concealed  until  the  Guinea  pig  had 
left  the  maze  and  was  then  given  him  as  a  reward. 

FIFTEEN] 


4 

22.8 

11.8 

14. 

7.3 

3. 

5 

5. 

1.6 

6.3 

1.1 

5. 

8 

27.1 

36.7 

6. 

3.3 

4. 

11 

69. 

75.8 

208. 

69.3 

312. 

4 

20.5 

18.2 

20. 

24. 

3. 

5 

4.2 

1.8 

4.3 

2.4 

8. 

8 

34.4 

44.1 

6.3 

3.1 

5. 

10 

59.1 

49.9 

19.3 

3.8 

25. 

18 

8.4 

3.4 

3.7 

1.1 

4. 

In  the  following  table  is  noted  the  time  and  accuracy  of 
the  guinea  pig's  forming  the  antagonistic  habit  of  making  the 
left  turn.  Only  his  reactions  in  leaving  the  maze  are  noted, 
his  entering  being  disregarded.  Fractions  are  omitted,  the 
next  higher  whole  number  being  used. 

Series  No.  Trials  Av.  Time  A.  D.          %  of  Errors 

1  6  113  165  50 

2  11  11  14  9 

3  4310 

4  17  2  1  0 

After  an  interval  of  forty-eight  hours  the  conditions  of 
the  first  part  of  the  experiment  were  resumed,  namely,  the 
left  door  was  locked  and  the  right  door  was  left  open.  The 
results  are  shown  in  the  following  table. 

Series  No.  Trials  Av.  Time  A.  D.          %  of  Errors 

1  15  11  7  41 

2  7520 

After  an  interval  of  six  hours,  the  conditions  were  again 
reversed.  In  the  following  table  are  shown  the  confusion 
effects. 

Series  No.  Trials  Av.  Time  A.  D.  %  of  Errors 

1  15                              22  19                            67 

2  25                                9  4                            40 

3  11                                8  3                            37 

The  Guinea  pig  seemed  to  compensate  for  his  inability 
to  form  the  left  turn  habit,  as  previously,  by  his  greater 
quickness  in  making  a  practical  trial  of  both  doorways.  He 
learned  that  if  one  door  was  locked  the  other  was  open  and 
he  substituted  a  method  of  trial  and  error  for  the  docility  of 
the  former  experiments.  Further,  he  acquired  a  negative 
reaction  to  the  sight  of  the  locked  door,  which  he  remembered 
was  locked  often  without  trying  it,  that  took  the  place  of  the 
lacking  positive  reaction  to  the  unlocked.  The  general  con- 
clusion from  the  above  results  is  that  frequent  alternation 
of  the  opposite  conditions  reduces  the  adaptability  of  the 
Guinea  pig  for  either  of  the  these  conditions  when  it  is 
afterwards  maintained  constantly.  This  last  method  of  re- 
action of  the  Guinea  pig's  was  well  suited  for  the  experi- 
ments in  Movement-odor  Association  described  in  the  fol- 
lowing section. 

[SIXTEEN 


Movement-odor   Association. 

A  watch  glass  covered  with  a  perforated  sheet  of  zinc 
was  placed  at  the  end  of  the  long  passage  at  which  point  the 
Guinea  pig  had  to  choose  between  the  right  and  left  turns. 
When  the  left  door  was  open  the  watch-glass  contained  a 
piece  of  absorbent  cotton  saturated  with  oil  of  peppermint. 
When  the  right  door  was  open  this  watch-glass  was  replaced 
by  another  containing  tincture  of  assafoedita.  Care  was 
taken  that  the  two  watch-glasses  should  offer  the  same  visual 
appearance  and  also  that  the  maze  should  be  well  aired  be- 
tween each  change.  As  the  time  of  the  turning  reaction  was 
so  largely  dependent  on  the  pig's  state  of  hunger  and  fatigue 
the  measurement  was  of  right  and  wrong  cases  only,  no  record 
being  taken  of  the  time. 

At  first  twenty-four  series  of  three  trials  each  were 
taken,  the  odors  and  the  unlocked  doorways  being  alternated 
every  three  trials.  The  Guinea  pig  was  considered  to  have 
failed  in  every  trial  in  which  he  tried  the  locked  doorway. 
No  punishment  was  used  at  the  locked  door. 

Considering  the  first  six  series  and  the  last  six  series 
under  each  of  the  two  conditions,  making  groups  of  eighteen 
trials  each,  the  results  were  as  follows: 

Peppermint  and   Left   Turn  Per   cent   of  Right  Cases 

First    six    series    55.5 

Second   six  series    38.8 

Average    47.15 

Assafoedita  and  Right  Turn  Percent  of  Right  Cases 

First    six    series     44.4 

Second  six  series    50. 

Average    47.7 

Average   of  all   72   trials    47.4 

The  above  series  extended  through  two  weeks.  During 
the  next  eight  days  seventy-two  more  trials  were  taken, 
equally  distributed  between  the  two  conditions,  that  is,  be- 
tween the  occurrence  of  assafoedita  and  the  open  right  door 
and  peppermint  and  the  open  left  door.  In  these  trials  a 
random  order  of  presenting  the  conditions  was  used,  but  the 
same  set  of  conditions  never  occurred  more  than  twice  con- 
secutively. The  results  were  as  follows: 

SEVENTEEN] 


Percent  of  Right  Cases 

Peppermint    and    left    58.3 

Assaf oedita    and    right     47.2 

Average 52.7 

The  Guinea  pig  showed  that  he  detected  the  difference 
between  the  assafoedita  and  the  peppermint  for  he  would 
often  draw  back  from  the  assafoedita  and  then  pass  it  rapidly, 
always  taking  care  to  jump  over  the  watch-glass.  He  usually 
acted  in  this  way  when  the  assafoedita  was  first  presented 
after  an  interval  of  some  hours,  and  he  never  acted  so 
toward  the  peppermint. 

The  results  are  not  ground  for  assuming  that  the 
Guinea  pig  benefited  at  all  from  the  practice,  although  the 
practice  was  equal  in  amount  to  that  which  was  sufficient 
for  creating  the  spatial  association  of  the  previous  experi- 
ment. 

Experiments  to  determine  the  guinea  pig's  ability  to 
give  different  specialized  reactions  to  two  sounds  were 
negative. 

Experiments  to  determine  the  Guinea  pig's  ability  to 
associate  different  end  terms  with  two  series  of  motor  re- 
actions, gave  fairly  positive  results,  showing  the  characteric 
reduction  of  time  and  errors. 


[EIGHTEEN 


SOME   RESULTS   OF   TRAINING  A  WHITE   MOUSE 

An  albino  mouse  was  used  in  these  practice  experi- 
ments. The  conditions  were  as  follows: 

A  drop-bridge  apparatus  was  used  which  consisted  of  a 
disc  of  pasteboard  mounted  on  an  inverted  glass  tumbler,  on 
the  top  of  which  the  animal  could  walk  about  but  from 
which  he  could  not  descend.  There  was  a  hinged  bridge  which 
could  be  propped  up  out  of  reach  of  the  animal  but  which 
might  be  lowered  by  pulling  a  string  which  passed  above  the 
disc.  The  string  was  attached  at  one  end  to  a  fixed  rod  and 
at  the  other  to  the  prop  which  held  up  the  bridge.  The  prop 
was  made  in  the  form  of  a  toggle  joint,  the  system  being 
barely  in  equilibrium.  This  made  necessary  only  a  slight 
pull  on  the  string  in  order  to  cause  the  bridge  to  descend,  and 
the  position  of  the  prop  was  so  adjusted  as  to  require  just 
slightly  more  than  a  chance  touch  on  the  string  to  bring  about 
the  fall. 

When  the  bridge  had  descended  it  formed  part  of  an 
incline  which  led  to  the  ground,  where  food  was  provided. 
There  were  two  motives  which  might  lead  the  animal  to  come 
down  from  the  disc;  the  presence  of  the  food  below,  and  the 
restlessness  or  general  diffusion  of  energy  which  caused  the 
animal  to  move  about. 

At  the  first  few  trials,  the  mouse  tried  to  descend  by 
climbing  down  the  sides  of  the  tumbler,  but  he  found  this 
impossible.  As  a  result  of  his  random  movements  he  finally 
(after  165  seconds)  pulled  the  string  and  the  bridge  fell  into 
place.  To  this  he  paid  no  attention,  apparently  not  realizing 
that  it  led  to  the  ground.  Twice,  before  he  at  last  managed 
to  climb  down  the  bridge,  he  ventured  along  it  a  few  steps 
but  returned  to  the  disc  on  top  of  the  tumbler. 

The  most  rapid  practice  results  were  seen  in  the  habit 
of  descending  the  bridge  after  it  had  been  dropped,  the 
habit  of  pulling  the  string  being  slowly  and  never  perfectly 
learned,  that  is,  the  mouse  always  combined  the  characteristic 
climbing-down  movement  with  the  string  pulling.  He  would 
get  his  nose  over  the  string  and  then  lean  over  the  edge  of 

NINETEEN] 


the  disc,  making  scrambling  movements  with  his  feet.  He 
need  not  have  leaned  over  so  far,  as  the  bridge  dropped  with 
less  pull  on  the  string,  and  he  could  have  omitted,  for  the 
most  part,  the  foot  movements,  so  that  the  reaction  was  not 
reduced  to  the  greatest  efficiency. 

These  movements,  however,  were  always  made  on  the 
side  where  he  could  reach  the  string,  even  though  he  some- 
times wandered  about  the  disc  at  random.  After  a  lapse  of 
five  weeks  he  did  at  first  revert  to  his  old  attempts  to  climb 
down  anywhere,  but  this  reaction  was  soon  corrected. 

In  the  following  table  are  stated  both  the  time  the  mouse 
took  to  drop  the  bridge  after  being  placed  on  the  disc  and 
the  time  he  took  to  descend  to  the  ground  after  the  bridge 
had  been  dropped. 


TABLE 

Series 

No.  Trials 

Dropping 
Av.  Time* 

Bridge 
A.  D. 

Descending 
Av.  Time            A.  D. 

1 

6 

58 

53 

37 

42 

2 

8 

27 

14 

41 

47 

3 

3 

12 

5 

5 

1 

4 

3 

10 

4 

6 

2 

5 

3 

11 

5 

9 

2 

6 

4 

18 

11 

7 

2 

7 

6 

13 

9 

10 

5 

8 

5 

13 

8 

14 

11 

9 

3 

12 

6 

9 

2 

10 

4 

10 

6 

8 

3 

11 

3 

38 

10 

80 

42 

12 

6 

24 

16 

36 

47 

13 

4 

10 

6 

7 

2 

14 

5 

6 

3 

9 

5 

*Time   given   in   seconds. 
The  time  elapsing  between  the  tenth  and  the  eleventh 
series  was  five  weeks,  whereas  that  between  all  other  adjacent 
series  averaged  twenty-two  hours,  with  a  maximum  interval 
of  thirty-six  hours. 


[TWENTY 


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DEC  2  ( 
DEC  5    1937 


Gaylord  Bros. 

Makers 

Syracuse,  N.  Y. 
PAT.  JAN.  21,  1908 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


